Drilling tool



March 18, 1958 H. w. slTToN ET AL 2,327,264

DRILLING TOOL 2 Sheets-Sheet 1 Filed Aug. 4, 1954 INVENTORS ATTORNEYMarch 18, 1958 H. w. sxTTcN ET AL 2,827,264

DRILLINQ TOOL 2 Sheets-Sheet 2 Filed Aug. 4. 1954 INVENTORS TTOR/VEYUnited States Patent C DRILLING TOOL Hugh W. Sitton'and Thomas H.Sitton, Corsicana, Tex.

Application August 4, 1954, Serial No. 447,758

4 Claims. (Cl. Z55-Q73) This invention relates to drilling vtools andmore particularly to tools adapted for use in the releasing of surfacecasing set ina Well bore, `or tubing cemented in such a bore, or forsimilar purposes;

In the drilling of wells and especially in the ldrilling and productionof oil and gas wells, surface casing is usually set and cemented in theupper endv of thewell bore, such casing providing anchoring means forsurface equipment used in carrying out the drilling and producingoperations. Such surface casing is frequently ot relatively largediameter to permit the introduction of drilling equipment whereby thedrilling operations may be carried on through the casing, and thecasingusually extends downwardly for several hundred feet from vthe groundlevel. The casing is usually cemented in place at the top and bottom bya surrounding body of cement which sometimes extends throughout theentire length of the casing.

A well in which the casing has been set in this manner isoften producedby the insertion of'a well tubing of smaller diameter than the casingwhich may also be cemented in place in the casing at one ormorelocations throughout its length. Due to the fact that the bores ofsuch wells are rarely straight, and because-of the relative tiexibilityof the production string or weil tubing, the tubing is usually notconcentrically disposed relative to the casing and bore, and may contactthe inner wall of the casing and bore at various locations throughoutits length.

When a well which has been equipped in this manner is abandoned, thesurface casing and tubing is usually left in the well, due to thediiculty of releasing them from the cement, which results in great lossof valuable material.

The present invention has for its chief object the provision` ofdrilling equipment which is adapted to be positioned about the exteriorof a pipe set in a well bore, such as a casing or tubing and which maybe operated to drill away the surrounding cement to release the-casingor tubing whereby the same may be recovered for reuse.

Another object of the invention is to provide drilling equipment of theimpact or percussion type embodying a sleeve-like drill adapted to bepositioned about the exterior of a casing or tubing and operable todrill away the surrounding layer of cement to release the casing ortubing therefrom.y

A further object of the invention is the provision of drilling equipmentwhich may be usedin connection with well tubing which has been cementedin a well bore or casing, and which is not concentric with the bore orcasing, to drill away the cement and release the tubing without cuttingorotherwise damaging the tubing. v

Another'object of the invention is toprovide drilling equipment of thekind referred to embodying-means for frice A still further object of theinvention is the provision of drilling equipment constructed for useinthe releasing and recovery of well pipe-such as casing or tubing whichhas been cemented in a well bore, which equipment is of simple designand rugged construction capable of long withstanding the hard conditionsof use andl rough treatment to which such equipment is customarilysubjected.'

The above and other important objects andV advantages of the inventionmay best be understood from the following detailed description,constituting a speciiication of the same when considered in conjunctionwith the annexed drawings, wherein- Figure 1 is a fragmentary sideelevational view illustrating a preferred form 'of the invention andshowing the equipment in use in the releasing of well casing fromthe-bore of a Well;

FigureZ isa cross-sectional view, taken along the line 2 2 of Figure 1,looking in the direction indicated by the arrows;

Figure 3 is a fragmentary, side elevational view partly broken. awayandV partly in cross-section, details of construction of' the drill ofthe inventionV as illustrated in Figure l;

Figure 4 is a fragmentary side elevational view of a somewhat differentform of the invention, showing the use of the same in the releasing of atubing string from a well;

Figure 5 is a cross-sectional View taken along the line 5-5 of Figure 4,looking inthe direction indicated by the arrows; and

Figure 6 is a cross-sectional view taken along the line 6-6 of Figure 5,looking vin the direction Vindicated by the arrows.

Referring now to the drawings in greater detail. the invention isillustrated in Figures 1, 2 and 3 in connection with its use in thereleasing of casing from a well whose bore is indicated at O, suchcasing, designated C, having been set in the bore in the rusual mannerwith or without cementing. In the present illustration the drillingequipment comprises a drill 10 of the impact or percussion type, whichis of generally tubular formation and of a size to fit over the outsideof the casing and to pass freely over any couplings or connectionstherein. The drill 10 has a lower end portion l2 which is cylindricaland which is provided at its lower end with a blade like edge formedwith cutters or teeth'. The edge portion may have au inner bevelledsurface i6 and the teeth i4 may be outwardly ared if desired, to secureeflicient cutting action and to guide the drill over any couplings orconnections in the casing without cutting or otherwise damaging thesame.

Above the cylindrical portion 12 the drill may be cut away along oneside to form an upper more or less semi.- cylindrical portion 18 whichmay have a longitudinal groove 2t? along its mid portion. The upper endportion of the drill may be provided with tapered edges, one of which isindicated at 22 in Figure 1 to aid in guiding the drill past anyexternal enlargements'in the casing such as a coupling or connection.When the drill is being withdrawn from ther well the upper edge portionof the cylindricalportion i2 may also be bevelled, as seen at-13 inFigure l, for the same purpose.l

A tubular stem or circulating pipe 24 is positioned. in the groove 2t?and secured to the drill inany suitable man'- ner as by welding, thisstern extending above the upper end of the drill and being open at itslower end. A pipe 26, which may be in the form of a exible tube or'hose,is attached to the upper end of the tubular stern 24 wherethev drill`may be raised-and lowered and fluid-may be circulated through the stern.

,In making use of this iorm'of the invention, the drill,

v carry away the cuttings or mud formed.-

. the cement or earth formation surroundingl lthecasing mayV then begradually drilled away from raround the casing, the drill thus formingan enlarged bore about the casing.

During the drilling operation VtheV bore thus formed may be-kept iilledor partly lled with water'supplied thereto through the pipe 26 andtubular stern 24. if desired water may beV circulated Ydownwardlythrough Vthe stem 24 to pass upwardly about the drill and casing to-When a suticient length of the Vcasing has been thus released from thewell bore'it mayV beI-uncoupled'or cut off and removed from the well bythe Vuse Vot" any convenient type of conventionalrequipment,provided forthat purpose.

A somewhat different form of the drilling equipment of the invention isillustrated in Figures 4, and 6, which is'adapted for use in releasing awelltubing which is not in a position concentric with the well bore andwhich may be in contact with the wall of the bore or the interior of awell casing therein at one or more locations. In Figures 4, 5 and 6, thewell bore orV casing is indicated at O, within which a well` tubing T ispositioned, the tubing being ,out of concentric relation to the bore,whereby the tubing is at certain location closer to or in contact withthe interior of the bore or casing. In this form of the equipment thedrill 12 is of generally tubular shape and is cutaway along one side, asindicated at 18', throughout its length. The opening 18' Yis of somewhatgreater width than the external diameter of-the tubing about which thedrillris tobe positioned, and is preferably Vprovided with inwardlybevelled side edges 22 throughout the length of the opening so that theVtubing Y' or any coupling or connection thereon may readily pass throughthe opening in positioning the drill about the tub- The drill 10 isformed with lower end cutters or teeth 14' similar to the teeth 14 ofthe drill 10 previously described, and has an inwardly bevelled surface16' which served as a means for grinding the drill past couplings in thetubing. The drill 10 has a longitudinal groove 20T along its mid portionin which a tubular stem 24 is secured in the same manner as in thepreviously described form of the invention, to which stem a pipe orhose, not shown, may be connected for raising and lowering the drill inthe manner previously described.

In making use of this form of the invention, the enlarged borre aboutthe upper end of the tubing may be started with the drill 10 of the formillustrated in Figures V1, 2 and 3, in the manner previously set forth..Vi/hen the drill in the bore, the tubing passing through the open- Ying 18 during such lowering of the drill.

By then rotating the drill 10 about the tubing and elevating anddropping the drill at positions where it will not become wedged betweenthe tubing and the wall of the bore, the cement may be drilled away andthe tubing released from locationswhere the tubing is not in vconcentricrelation to the well bore.. i v

After the drill 10 has been thus used to clear a `location where thetubing is closeV to or in contact with the wall of the bore, it may bewithdrawn and the drill 10' againuse-d to carry out further drillingwhere the tubing is spaced inwardly from the wall of the bore. In thismanner substantial lengths of tubing may be released and recovered fromthe well,'without danger of cutting through the tubing at locationswhere the tubing is close Y to or in contact with the wall of the bore.

In other respects the drill 1,0 is operated like the drill 10, waterbeing supplied to Vtherbore through the tubular stem 24 in thesamemanner as previously described.

It will thus be seen that the invention constructed and operated asdescribed above'p'rovides `drilling equipment which is economicalinconstruction and eicient in operation and by which valuable wellcasing or tubing, which would otherwise be lost, may be released andrecovered for further use.

While the invention has been disclosed herein in connection with certainspecific embodiments of the same, it will'beV understood that this isintended by wayof illustration only, and that'numerous changes can bemade Y in the structure and arrangement of the drills without departingfrom the spirit of the invention or the scope of the appended lclaims.

Having thus clearly shown and described the invention, what is claimedas newand desired to secure by Letters Patent is: Y

1. A drilling tool for drilling around a pipe set in a well borecomprising a tubular drill shaped to tit over a pipe in a well bore andto operate against the formation around said pipe, cutters on the lowerend of the drill, said drill having an external longitudinal grooveterminating above Ythe lower end of the drill and a tubular stem in saidgroove connected to the drill and whose lower end is open.

2. A drilling tool for drilling around a pipe set in a well boreVcomprising a drill of generally tubular formation having a cylindricallower end portion shaped to tit over a pipe in a'well bore and tooperate against .the formation around said pipe and aV portion abovesaid cylindrical portion which is arcuate in cross-section, cutters onthe lower end of the drill, said lower end portion having an upperinwardly bevelled edge portion positioned to engage an externalenlargement on the pipe to guide the drill past said enlargement, saiddrill having an eXternal longitudinal groove terminating above the lowerend of the drill, and a tubular stern in said groove connected to thedrill and whose lower end is open.

3. A drilling tool for drilling around a pipe set in a well borecomprising a drill of generally tubular formation having a cylindricallower end portion shaped to tit over a pipe in a well bore and tooperate against the formation around the pipe and an arcuate portionabove said cylindrical portion, the lower end of the drill beingoutwardly flared, cutters on the lower end of the drill, said lower endportion having an upper inwardly bevelled edge portion positioned toengage an external enlargement on the pipe to guide the drill past saidenlargement.

4. A drilling tool for drilling around a pipe set in a well borecomprising an elongated drill of arcuate formation in cross-sectionshapedfto partially surround a pipe in a well bore and to operateagainst the formation around the pipe, said drill having an externallongitudinal groove yand a tubular stem positioned in said groove andconnected to the drill and whose lower end is open.

References Cited in the file of this patent UNITED STATES 'PATENTS187,670 Poney et ai Feb. 2o, 1377 295,045 Parker Mar. 11, 1884 880,881Hardsocg Mar. 3, 1908 1,345,299 Welsh June 29, 1920 1,882,906 RenterOct. 18,1932 2,214,970 Mooney Sept. 19, 1940 v 2,305,200 Sitton Dec. 15,1942 2,449,841 Claypool et al Sept. 21, 1948

